The invention relates to a method and device for operating tank farm systems in a fixedly piped interconnection with piping systems for liquids, particularly for use in plants subjected to high microbiological quality requirements for product treatment and for product transfer in the foodstuff and beverage industries, pharmacy, and biotechnology.
The microbiological requirements which are made nowadays to production plants in the field of the foodstuff and beverage industries, pharmacy, and biotechnology grow to the extent at which measuring procedures to establish microbiological loads are improved and the limits of detectability are reduced for substances of any types. As a typical example, which is also vicarious for other applications, the document quotes fermentation processes below (e.g. the fermentation sector in brewhouses). Problems will occur here when the setup and arrangement of piping between fermentation tanks and their peripheries, in an interaction with production flows, cause situations which create an environment that encourages the growth of germs. The piping concepts employed nowadays in this sector in conjunction with a tank farm system involve relevant hazard potentials which should be taken into account and should be eliminated, if possible, already in devising such plant concepts. The piping concepts which are favored nowadays are briefly set forth below and indications are made to show where actions are indispensable, taking into consideration the steadily rising microbiological quality requirements.
The relevant art which probably is the most widespread one in the aforementioned sector will be depicted below by the example of a tank farm system 1 (FIG. 1) of a brewhouse that comprises five fermentation tanks 1.1 to 1.n. Their number may be readily extended, for which reason the fifth tank is designated as 1.n. Each of the tanks 1.1 to 1.n is joined to a first filling pipe line 2.1 (a so-called functional line) for filling F1 (wort WZ) and a second filling pipe line 2.2 for filling F2 (yeast H), an emptying pipe line 3 for emptying E1 (new beer J) or for emptying E2 (yeast expulsion H*), a cleaning pipe line 4 for tank/pipe cleaning R1 (cleansing agent R), and a pipe cleaning 12 discharge line for pipe cleaning R2 (cleansing agent R). The junctions at which incompatible media could oppose each other (product P in general, representing wort WZ or yeast H or new beer J, for example, and a cleansing agent R each) are fitted with so-called mix-proof valves. In the present example, this is a second valve 7.2.1.1 to 7.2.1.n which each separates a tank discharge line 8.1.1* to 8.1.n*, in which the respective tank volume is for the tanks 1.1 to 1.n, from a respective discharge line 8.1.1 to 8.1.n that leads to a so-called valve block VB. The embodiment of FIG. 1 represents a technically improved piping version already; simpler versions will be briefly outlined below.
The simplest piping system, which is not shown, is to combine the functions of filling F1, F2, emptying E1, E2, and tank and pipe leaning R1, R2 in the central valve block VB and to lead the tank discharge lines 8.1.1* to 8.1.n* to this valve block VB in different lengths without intercalating the aforementioned second valves 7.2.1.1 to 7.2.1.n. Although such an arrangement will result in a relatively short traverse distance a1 between so-called traverses 9.1.1 to 9.1.n+1 of the valve block VB, but also a relatively long tank discharge line 8.1.1* to 8.1.n*, at least in part, from the individual tank 1.1 to 1.n. In such a manner of installation, the tank discharge line 8.1.1* to 8.1.n* and the traverse 9.1.1 to 9.1.n each associated therewith of the valve block VB form part of the respective tank 1.1 to 1.n. Here, the drawback is that the tank volume in the respective tank 1.1 to 1.n inevitably is also the contents each of the tank discharge line 8.1.1* to 8.1.n* associated therewith and the traverse 9.1.1 to 9.1.n which joins it, and that this portion takes part in the treatment process (the fermentation process, in this embodiment) in the tank 1.1 to 1.n only to a very limited degree because of the geometry and arrangement conditions, which also results only in a restricted exchange of substance there.
The foregoing drawbacks can be mitigated somewhat if the tank discharge lines 8.1.1* to 8.1.n* are laid at a slope as large as possible to the valve block VB. As a result, a certain convection and, thus, a stirring action which favors the exchange of substances will arise because of the gas bubbles rising up to the respective tank 1.1 to 1.n within each associated tank discharge line 8.1.1* to 8.1.n*.
However, the main problem encountered for the tank 1.1 to 1.n fixedly piped to the valve block VB, that cannot be disconnected in each case in its tank discharge line 8.1.1* to 8.1.n* leading to the valve block VB, substantially is that is it impossible to provide for an expulsion of the product P and a separate cleaning R1 of the tank discharge lines 8.1.1* to 8.1.n* and the associated traverses 9.1.1 to 9.1.n.
In such an arrangement, for example, if the tank 1.2 is filled with wort WZ the end of the filling line (the first filling pipe line 2.1 here) between the valves V12 and V16 of the valve block VB and the end of the traverse 9.1.2 between the valve V12 and a valve V52 will be filled as well. Those line volumes virtually would not allow to be expelled and wound not even if a so-called expulsion device A1 extending from a expulsion pipe line 6 was passed into the tank, which is tank 1.2 in the present case. As a result, there is a non-definable mix in the traverse 9.1.2 that consists of wort WZ, possibly yeast H if yeast was metered after wort had been added, and expulsion water. This mix will remain there until the tank 1.2 is emptied and cleaned again after a few days.
From brewhouse technological interconnections, it has been known, and cannot be ruled out either, that the wort WZ contains germs which cannot be found to exist as long as they are suppressed by an active outer field of the yeast H. Such slumbering germs, however, begin to multiply as soon as favorable conditions arise for a relevant propagation. For example, such conditions are created by the fact that the mix of wort WZ, yeast H, and expulsion water W, which is in the respective traverse 9.1.1 to 9.1.n, will heat up because of the hot cleaning (at 85 to 90° C.) of the functional lines that takes place every day. Temperatures up to 35° C. will then be readily achieved there so that this creates optimal conditions for germ multiplication depending on the germ strain, all the more so as the yeast H, after reaching the final fermentation level, is no longer active and will settle. As a result, the yeast stops its germicidal performance. The germs which thus multiply without any control and virtually cannot be reached are entrained into other tanks and production areas be-cause of the emptying, yeast extraction, and repumping operations that succeed, and will be a burden on the product.
The version illustrated in FIG. 1, which is technically improved as compared to the foregoing, simpler piping version, allows to subject a portion of the discharge line 8.1.1** to 8.1.n** and the respective discharge line 8.1.1 to 8.1.n which joins it to separate pipe cleaning R1 via a tank cleaning feed line 11.1.1 to 11.1.n irrespective of a cleaning of the respective tanks 1.1 to 1.n. This is always accomplished via a first valve 7.1.1.1 to 7.1.1.n and the second valve 7.2.1.1 to 7.2.1.n of which the first one separates the first portion of the discharge line 8.1.1** to 8.1.n** from the cleaning pipe line 4 and the second one which separates this portion from each succeeding discharge line 8.1.1 to 8.1.n, which separate the respective associated tank discharge line 8.1.1* to 8.1.n* from the mentioned discharge lines 8.1.1** to 8.1.n**.
When the plant periphery is configured accordingly and the time-scheduled production flow schema allow to do so this pipe cleaning R1 can be carried out traverse by traverse after each filling and emptying operation or once a day by fully clocking all discharge lines 8.1.1 to 8.1.n along with the traverses 9.1.1 to 9.1.n in each cleaning phase of the tank and pipe line system.
For example, the cleaning procedure for the traverse 9.1.3 is as follows:
The cleansing agent R is fed to the site through the cleaning pipe line 4 in the path of the pipe cleaning R1. It passes into the portion of the discharge line 8.1.3** via the first valve 7.1.1.3 and, thence, into the discharge line 8.1.3 via the second valve 7.2.1.3 and, finally, flows into the traverse 9.1.3 in order to get into the line 4 from this point through the valve V53 of the valve block VB and to leave the illustrated piping system subsequently via a second pump 14.
The lines 10.1 to 10.3 which cross the traverses 9.1.1 to 9.1.n+1 are adapted to be cleaned via pipe cleaning devices R2 which are acted on by the supply of cleansing agent R via a second pipe cleaning feed line 5.2 and optionally by an actuation of valves which are not referred to in detail. During this pipe cleaning R2, the cleansing agent exits the piping system through the pipe cleaning discharge line 12. A lock-up valve 15 allows to effect the tank and traverse cleaning R1 via the cleaning pipe line 4 with no need for this line between the tank 1.1 and the second pump 14 to be flown through by the cleansing agent R as well.
The cleaning of the fourth line 10.4 (pipe cleaning R2) which opens out into the discharge pipe line 3 through a first pump 13 is effected by admitting a cleansing agent R through a first pipe cleaning feed line 5.1. On its route into the fourth line 10.4, the cleansing agent R initially passes through a second valve V401 preceding the valve matrix and, subsequently, through a preceding first valve V40.
What can be deduced from the foregoing concise instructions for cleaning the piping and tank farm system is that an arrangement of a multiplicity of valves and additional pipe line portion permits to clean substantially all areas of the interconnected piping system.
However, the piping system of a known type illustrated in FIG. 1 also results in regions of non-expelled product within the valve block VB. A non-expelled product P will be washed out during the cleaning which follows and, hence, constitutes a loss of product via the first filling pipe line. Referring to the aforementioned filling of the tank 1.2 with wort WZ via the first filling pipe line 2.1, a brief indication is to show what the mentioned loss of product is in this definite case. If expulsion water W is introduced in the path of the expulsion device A1 via the expulsion pipe line 6 it is possible to expel that wort WZ, which has built up in the discharge lines 8.1.2** and 8.1.2 and in the traverse 9.1.2 which joins it and accumulates up to a valve V42, into the tank 1.2. The volume contained in the traverse 9.1.2 in the region between valves V42 and V52 as well as the volume contained in the pipe line 10.1 in the area between V12 and V16 cannot be captured through the aforementioned expulsion device A1 via the expulsion pipe line 6. Thus, the wort WZ is lost in those pipe line areas.
This loss in the aforementioned line portions which are in communication with the first filling pipe line 2.1 can admittedly be diminished by extra installation expenditure which makes possible a so-called “counter-expulsion”. However, such a measure mostly is worthwhile only for very long lines within the valve block VB.
In addition, further measures are known which are apt to further reduce the loss of product. One of such measures consists in expelling the product from the lines in question by means of a so-called “pipe circuit expulsion”, which does not produce any appreciable “dead ends” in the piping system. In any case, the “counter-expulsion” or “pipe circuit expulsion” will necessitate a significant installation expenditure. Such solutions involve that the traverses of the valve block VB and the discharge lines leading away from the tanks are always cleaned in a pure cleaning procedure which is independent on tank cleaning. To avoid restrictions in time because the discharge line is occupied by tank cleaning the tank cleaning return line is directly connected to the tank and does not use the discharge line.
The assembly to realize the aforementioned “pipe circuit expulsion” is subjected to certain restrictions because the pipe circuit on the valve block VB can presently be used for one cleaning operation only. Restrictions can only be avoided by a well-timed production management or by the installation of a further pipe circuit.
As a conclusion, let us give a summary of the essential drawbacks which are inherent to all tank farm systems which work in a fixedly piped interconnection with valve blocks VB in which a multiplicity of valves are disposed in the form of a matrix:                The branching points of such valves are followed by pipe line portions from which the product P usually cannot be expelled (example: a portion of the discharge line 8.1.2**; a portion of the first line 10.1 adjacent to V12 to V16; the traverse 9.1.2 adjacent to V42 to V52).        A non-defined mix of various products P (WZ, H, J) and expulsion water W will often form in the so-called “dead ends”.        The non-expelled product P will turn into a loss during the succeeding cleaning procedure at the latest.        Non-defined product mixes cause negative burdens on the desired product P that depend on their compositions, because non-controlled processes might run. Such processes can lead to an undesirable growth of germs.        Increases in temperature, e.g. as a result of hot cleaning operations, cause an environment in the traverses of the valve block that encourages an undesirable growth of germs.        Specifically in horizontally disposed valve blocks and in case of long lines, the product P contained therein is not involved in the treatment process in the tank. Thus, no exchange of substance or merely a low exchange will take place in the pipe line portions in question.        Avoiding areas of a non-expelled product P in the classical valve matrixes discussed above, diminishing losses of product, and allowing those areas to be separately cleaned even if the tank is full requires a very large expenditure in the periphery of the valve matrix that cannot be realized in most cases for reasons of economy and leads to difficult-to-survey piping systems which necessitate a lot of maintenance. For these reasons, when the problems are tackled in practice, compromising solutions are found that exhibit more or less pronounced restrictions.        The air which has entered the tank discharge line and the discharge line joining it in conjunction with the traverse during tank cleaning prevents the piping system from being properly cleaned.        